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    Ionically cross-linked alginate hydrogels as drug delivery systems for analgesics in broiler chickens : thesis presented in partial fulfilment of the requirement for the degree of Masters of Science in Chemistry at Massey University, Palmerston North, Manawatu, New Zealand
    (Massey University, 2017) Booty, Samuel James
    Treating birds with analgesic drugs requires continuous injections of near lethal concentrations to maintain the therapeutic dose in the blood plasma. This is due to birds having higher metabolic rates than mammals. Therefore, there is a need to develop drug delivery systems that can control and slow down the release of analgesics in birds. This study was designed to analyse the sustained release of the model analgesics, sodium salicylate and sodium aspirin, from ionically cross-linked alginate hydrogels, in in vitro and in vivo experiments using broiler chickens as the model bird. Analgesic loaded hydrogels separated into two layers, unlike the homogeneous blank hydrogels. This was labelled as the separation effect. Swelling studies indicated the absence of the insoluble cross-linked alginate material in the hydrogels where the separation effect occurred, with most of the hydrogels dissolving back into the medium. The highest equilibrium swelling percentage achieved in the loaded hydrogels was 68 %. In comparison, the highest equilibrium swelling percentage in the blank hydrogels was 622 %. In vitro drug release profiles showed that the hydrogels released up to 100% of the sodium salicylate within 3.33 hours. In contrast, the hydrogels containing sodium aspirin released only 35 % of the encapsulated drug. Hydrogels containing a drug concentration of 150 mg/mL were injected into the model birds at a dose rate of 150 mg/Kg. No chicken reacted negatively to the hydrogel injection. In vivo results indicate sustained release of the model analgesic from the hydrogels compared to the release from the aqueous solutions of the drug. The effective concentration for an analgesic effect of sodium salicylate was maintained by the group injected with an aqueous solution of sodium salicylate 18 hours after the injection. The groups injected with the hydrogel with the maximum calcium chloride content saw the largest sustained release, with the plasma concentration of sodium salicylate remaining over the effective concentration for up to 36 hours after the injection. Keywords: Sodium salicylate, sodium aspirin, hydrogel, analgesia, sustained release, broiler chicken.
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    Measurement of true ileal calcium digestibility of feed ingredients for broiler chickens : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Institute of Veterinary, Animal and Biomedical Science (IVABS), Massey University, Palmerston North, New Zealand
    (Massey University, 2017) Anwar, Muhammad Naveed
    The recent interest towards the use of digestible phosphorus (P) in poultry feed formulations necessitates the measurement of true calcium (Ca) digestibility of feed ingredients because of the close relationship between these two minerals for their absorption and post absorptive utilisation. When this thesis research was initiated, no published data were available on Ca digestibility of feed ingredients for broiler chickens. The major objective of the studies reported in this thesis was to determine the true Ca digestibility of feed ingredients for broiler chickens. In total, nine studies were conducted. The first study (Chapter 4) was conducted to determine the effect of methodology on ileal endogenous Ca losses. Three methods, namely feeding a Ca- and P-free diet, maize gluten meal based diet and egg albumen based diet, were used. Ileal endogenous Ca losses differed among different methodologies. The highest ileal endogenous losses of 125 mg/kg dry matter intake (DMI) were recorded on the Ca- and P-free diet, followed by 77 and 43 mg/kg DMI on maize gluten meal and egg albumen diets, respectively. In the second and third studies (Chapters 5 and 6), regression and direct methods, respectively, were used to determine the true Ca digestibility of meat and bone meal (MBM). The true Ca digestibility coefficient of MBM samples were ranged from 0.41 to 0.60. No difference was observed between true Ca digestibility coefficients of MBM determined by regression and direct methods. Since the direct method is less laborious and cost effective compared to regression method, this method was used in subsequent studies (Chapters 7 to 10) to determine the true Ca digestibility of a range of Ca sources. In fourth and fifth studies (Chapters 7 and 8), the influence of dietary P, particle size and Ca to non-phytate P ratio was investigated on the true Ca digestibility of limestone for broiler chickens. The true Ca digestibility of three limestone samples varied from 0.56 to 0.62. Supplementation with recommended dietary P (4.5 g/kg) increased the true Ca digestibility of limestone when compared to diets without P. An increase in particle size from <0.5 to 1-2mm improved the true ileal Ca digestibility of limestone. Widening the Ca to non-phytate P ratio reduced the true Ca digestibility of limestone for broiler chickens. The sixth study (Chapter 9) was conducted to determine the effect of Ca source and particle size on the true Ca digestibility and total tract retention. Limestone and oyster shell were used as Ca sources. No difference was observed between the true Ca digestibility of limestone and oyster shell. An increase in particle size from <0.5 to 1-2 mm increased both the Ca digestibility and retention of both Ca sources, and increased the Ca concentration of gizzard contents. The study reported in Chapter 10 was conducted to determine the true Ca digestibility of dicalcium phosphate (DCP), monocalcium phosphate (MCP), canola meal, poultry by-product meal and fish meal, and to compare the effect of dietary adaptation length on true Ca digestibility of DCP and MCP. The true Ca digestibility coefficients of these feed ingredients were lower than MBM, limestone and oyster shell, and ranged from 0.24 to 0.33. It was speculated that the length of adaption to the assay diets may be responsible for the lower than expected estimates. The effect of dietary adaptation length (24, 48 or 72 hrs) was subsequently examined, but had no effect on true Ca digestibility of DCP and MCP. In the final study (Chapter 11), the true Ca digestibility of DCP was determined using different methodologies (regression, difference and direct methods). The true Ca digestibility coefficients of DCP were 0.34 and 0.21 with direct and different methods, respectively. A very low digestibility coefficient of 0.13 was determined by the regression method. In conclusion, the true Ca digestibility coefficient of major Ca sources (limestone, oyster shell and MBM) is not high and varied from 0.40 to 0.70. Particle size of limestone and oyster shell influenced Ca digestibility, with coarser particles having higher digestibility. The direct method appears to be suitable for the determination of true Ca digestibility of limestone, oyster shell and MBM, but may not be appropriate for other Ca sources with intrinsic imbalance of Ca and P.
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    Age and cereal effects on the performance, gut parameters and nutrient utilisation in the newly hatched broiler chick : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science at Massey University
    (Massey University, 2007) Thomas, Donald V
    This study was intended to provide a platform for enhanced nutritional management of modern broilers through better understanding of changes in nutritional utilisation in the newly hatched chick. Differences in performance, nutrient utilisation and the development of the gastrointestinal tract in the young broiler chicken fed diets based on different cereals were examined. Diets based on wheat, sorghum and maize and formulated to contain iso-energy and iso-lysine levels were fed to broiler chicks between days 1 and 14 post hatch. Birds fed the maize based diet grew faster (P < 0.05) than those fed the sorghum based diet. Weight gains of birds fed the wheat based diet did not differ (P > 0.05) from those fed either maize or sorghum based diets. There were numerical differences in feed:gain with the sorghum based diet having the highest feed per gain, but the differences were not significant (P > 0.05). The relative weights of digestive organs and digestive tract showed no significant cereal treatment differences (P > 0.05). The treatments had no effect (P > 0.05) on the relative length of the digestive tract or gut histology measurements. The wheat based diet contained a commercial xylanase which may have ameliorated the digesta viscosity of this diet and reduced the NSP effect on gut structure and morphology. Furthermore, gut morphology samples showed a high degree of variation, suggesting that a large sample size would be necessary for significant differences to be determined. Two experiments were conducted to investigate cereal and age effects on nutrient utilisation in the young broiler chicken. Experiment 1 determined the nitrogen-corrected apparent metabolis able eneigy (AMEn) of diets based on wheat, sorghum and maize during 14 days post-hatch. Changes in the total tract digestibility of starch and fat were also measured. The second experiment was conducted to confirm the results of Experiment 1 using wheat and maize based diets and was of 21 days duration. In both experiments, changes to AMEn with age were similar for all diets, declining from day 3 to days 5-9 and increasing again. In experiment 1, cereal effects were significant (P < 0.05) with maize and sorghum based diets having higher AMEn values than the wheat based diet, In experiment 2, cereal effects were significant (P < 0.05) with the maize based diet having a higher AMEn than the wheat based diet. In experiment 1, total tract starch digestibility determined for days 5, 7 and 14 showed no cereal differences (P > 0.05). Age effects were significant (P < 0.05) with starch digestibility declining from day 5 to day 7, and then increasing again. Total tract fat digestibility on day 7 was significantly lower for the wheat and sorghum based diets than for the maize based diet, but no cereal differences (P > 0.05) were observed on days 5 or 14. Age effect was highly significant with fat digestibility declining from day 5 to day 7 and increasing again. These results showed that nutrient utilisation is compromised during the first week of life of the broiler chick. Samples of diets and excreta from Experiment 1 were analysed for minerals to determine changes in the apparent total tract mineral retention of the broiler chick during the first two weeks post-hatch. The diet and excreta samples were analysed for calcium, phosphorus, potassium, sodium, magnesium, iron, manganese, zinc and copper, and their retention was determined. The retention coefficients of individual minerals differed widely and the retentions of major minerals were much greater than those of minor minerals. The cereal effects were significant (P < 0.05) for several minerals, with a general tendency for the sorghum diet to have greater retention than maize or wheat diets. Age effects were significant (P < 0.05) for all minerals. In general mineral retention coefficients were higher at day 3, declined to day 7 and remained unchanged to day 14. Decline in mineral retention with age was similar in all three diets. The studies reported in this thesis investigated the performance and nutrient utilisation of broiler chicks fed diets based on wheat, sorghum or maize. A significant reduction in nutrient utilisation over the period 5-9 days of age was observed suggesting that nutrient digestion and absorption is compromised during the first week of life of the broiler chick. Further work is required to identify the specific causes of the decline in digestibility during the early stages of chick development.